﻿Shader "Study/Chapter6/DiffusePixelLevel"
{
	//逐像素漫反射光照
	Properties
	{
		_Diffuse("Diffuse",Color) = (1,1,1,1)
	}
	SubShader
	{
		Pass
		{
			Tags { "LightMode"="ForwardBase" }
			CGPROGRAM
			#pragma vertex vert
			#pragma fragment frag
			
			#include "Lighting.cginc"

			float4 _Diffuse;

			struct a2v
			{
				float4 vertex:POSITION;
				float3 normal:NORMAL;
			};

			struct v2f
			{
				float4 pos:SV_POSITION;
				fixed3 worldNormal:COLOR;
			};
			
			v2f vert(a2v v)
			{
				v2f o;	
				o.pos = mul(UNITY_MATRIX_MVP,v.vertex);
				o.worldNormal = mul(v.normal, (float3x3)_World2Object);
				return o;
			}

			float4 frag (v2f i) : SV_Target
			{
				fixed3 ambient = UNITY_LIGHTMODEL_AMBIENT.xyz;
				fixed3 worldNormal = normalize(i.worldNormal);
				fixed3 worldLightDir = normalize(_WorldSpaceLightPos0.xyz);
				fixed3 diffuse = _LightColor0.rgb * _Diffuse.rgb * saturate(dot(worldNormal,worldLightDir));
				fixed3 color = ambient + diffuse;
				return fixed4(color,1.0);
			}
			ENDCG
		}
	}

	FallBack "Diffuse"
}
